(1) Field of the Invention
This invention relates to removing material from the surface of a wafer using Chemical Mechanical Polishing and more particularly to the use of temperature compensation to achieve uniform removal rates across the entire surface of the wafer.
(2) Description of the Related Art
Chemical Mechanical Polishing, CMP, is frequently used to planarize wafers by removing material from the surface of a wafer. CMP uses a rotating wafer carrier to hold a wafer against a polishing pad held by a rotating platen. The polishing also uses a polishing slurry dispensed on the polishing pad.
U.S. Pat. No. 5,196,353 to Sandhu et al. describes a method and apparatus for thermally mapping the surface of a wafer during Chemical Mechanical Polishing. The thermal map information is then analyzed and used to modify the polishing process parameters.
U.S. Pat. No. 5,486,129 to Sandhu et al. describes a system and method for Chemical Mechanical Polishing wafers using a polish control subsystem and a polishing head with localized pressure applicators for controlling localized pressure at individual regions of the wafer. The polish control subsystem allows control of operational subsystems such as temperature at the wafer surface, platen velocity, and localized pressure.
U.S. Pat. No. 4,910,155 to Cote et al. describes a method for Chemical Mechanical Polishing insulators, such as silicon oxide and silicon nitride, formed on the surface of wafers. The method uses a slurry with particulates having a hardness commensurate to the hardness of the insulator to be polished at a temperature between 85.degree. F. and 95.degree. F. to maximize both polishing pad lifetime and planarization uniformity.
U.S. Pat. No. 5,422,316 to Desai et al. describes a Chemical Mechanical Polishing system for polishing wafers which uses a polishing limiter to limit the reduction in thickness of the wafer during polishing.
This invention describes a method and apparatus for achieving a uniform material removal rate across the entire surface of the wafer. The temperature of circular segments of the wafer carrier and circular segments of the platen are individually controlled. The temperature of the wafer carrier circular segments and platen circular segments are individually controlled to compensate for pressure variation across the wafer and variation of the relative velocity between the wafer and platen across the wafer to produce a uniform material removal rate across the entire surface of the wafer.